Belfast_md

Belfast road network changed to 20mph

Belfast city center implementation zone

Belfast metropolitan area

Belfast’s control zone

Time series Analysis

Mapping accidents with roads: 2013

##   a_speed a_ID
## 1      30   59

Mapping accidents with roads: 2014

##   a_speed a_ID
## 1      30   84

Mapping accidents with roads: 2015

##   a_speed a_ID
## 1      20    2
## 2      30   86

Mapping accidents with roads: 2016

FALSE   a_speed a_ID
FALSE 1      20   28
FALSE 2      30   51

Mapping accidents with roads: 2017

FALSE   a_speed a_ID
FALSE 1      20   26
FALSE 2      30   59

Mapping accidents with roads: 2018

##   a_speed a_ID
## 1      20   28
## 2      30   47

Mapping accidents with roads: 2019

##   a_speed a_ID
## 1      20   21
## 2      30   52

Count pre 20mph

##   a_speed a_ID
## 1      20    2
## 2      30  236

Count post 20mph

##   a_speed a_ID
## 1      20  103
## 2      30  202

Output column: Changed to 20 mph

##   Urban_Rural a_ctype CLASS              NAME ROAD_NUMBE
## 1       RURAL      13     A       YORK STREET      A0002
## 2       RURAL      13     A       YORK STREET      A0002
## 3       RURAL      13     A       YORK STREET      A0002
## 4       RURAL      13     A       YORK STREET      A0002
## 5       URBAN      13     A       YORK STREET      A0002
## 6       URBAN       2     A CHICHESTER STREET      A0020

Mapping accidents with zones( metropolitan area) : 2013

Mapping accidents with zones ( metropolitan area): 2014

Mapping accidents with zones ( metropolitan area) : 2015

Mapping accidents with zones ( metropolitan area) : 2016

Mapping accidents with zones ( metropolitan area) : 2018

Mapping accidents with zones ( metropolitan area) : 2019

Total accidents in the implementation zone

## [1] 7268

Table: Average annual road traffic collision rates in the metropolitan area of Belfast

Table 1: Average annual road traffic collision rates in the city of Belfast (PSNI data)

Type	collisions pre-20mph (2013 / 2016 - 3 years)	collisions post-20mph (2016 / 2019 - 3years & 11 months)	rate pre-20mph	rate post-20mph	diff in rates = pre - post	Perc.diff.rates = (pre - post) / pre * 100
Streets changed
Streets changed to 20mph	238	305	79.33	77.81	1.52	2
Streets stayed
20mph, 30mph	3630	4576	1210.00	1167.35	42.65	4
All streets
All streets	3868	4881	1289.33	1245.15	44.18	3
Note:
1 All accidents at 20mph, 30mph

Table: Average annual road traffic collision rates in the city centre of Belfast

Table 1: Average annual road traffic collision rates in the city of Belfast (PSNI data)

Type	collisions pre-20mph (2013 / 2016 - 3 years)	collisions post-20mph (2016 / 2019 - 3years & 11 months)	rate pre-20mph	rate post-20mph	diff in rates = pre - post	Perc.diff.rates = (pre - post) / pre * 100
Streets changed
Streets changed to 20mph	237	305	79.00	77.81	1.19	2
Streets stayed
20mph, 30mph	329	432	109.67	110.20	-0.53	0
All streets
All streets	566	737	188.67	188.01	0.66	0
Note:
1 All accidents at 20mph, 30mph

Effect estimate in all accidents ( metropolitan area )

Effect estimate

Tax year	2013/14	2014/15	2015/16	2016/17	2017/18	2018/19	2019/20
Annual number of collisions in roads changed to 20mph	1240	1340	1288	1313	1270	1177	1121
Rate per year	1240	1340	1288	1313	1270	1177	1245.56
% reduction in collisions	5.02

Calculations
A + B + C / 3	1289.33
D + E / 3.9	1251.54
A - B / A	-8.00
B - C / B	4.00
Unadjusted_estimate	3.00
Secular_trend	-2.00
Note:
1 A : accidents 2013/14 ( 1 year )
2 B : accidents 2014/15 ( 1 year )
3 C : accidents 2015/16 ( 1 year )
4 D : accidents 2018/19 ( 1 year )
5 E : accidents 2019/20 ( 11 months )

Effect estimate in all accidents ( on the roads that changed to 20mph )

Effect estimate

Tax year	2013/14	2014/15	2015/16	2016/17	2017/18	2018/19	2019/20
Annual number of collisions in roads changed to 20mph	194	182	190	182	191	190	174
Rate per year	194	182	190	182	191	190	193.33
% reduction in collisions	-1.06

Calculations
A + B + C / 3	188.67
D + E / 3.9	188.97
A - B / A	6.00
B - C / B	-4.00
Unadjusted_estimate	0.00
Secular_trend	1.00
Note:
1 A : accidents 2013/14 ( 1 year )
2 B : accidents 2014/15 ( 1 year )
3 C : accidents 2015/16 ( 1 year )
4 D : accidents 2018/19 ( 1 year )
5 E : accidents 2019/20 ( 11 months )

Count accidents in Control Zone : City Center –> Central ( Ards )

## [1] 175

Output column : Output Area code ( OA_code )

##    Urban_Rural a_ctype OBJECTID_1
## 9        URBAN      13       <NA>
## 11       URBAN       2       <NA>
## 30       URBAN      13       <NA>
## 37       RURAL      13       <NA>
## 60       URBAN      13       <NA>
## 62       URBAN      13       <NA>